Atlantic City, February 1924: After barely surviving an overthrow by gangster Gyp Rossetti, Nucky Thompson is laying low at the end of the Boardwalk. But the calm will be short-lived, as Nucky faces new challenges, including a clash with the mayor, a battle with his brother Eli over Eli's college-age son, and the irresistible lure of lucrative - and perilous - opportunities in Florida.

From Terence Winter, Emmy(R) Award-winning writer of "The Sopranos," and Academy Award(R)-winning director Martin Scorsese, BOARDWALK EMPIRE is set in the 1920s during Prohibition, and chronicles the life and times of Enoch "Nucky" Thompson. The Emmy(R)- and Golden Globe-winning drama series kicks off its 12-episode fourth season SUNDAY, SEPT. 8 (9:00-10:00 p.m. ET/PT), exclusively on HBO, followed by other episodes on subsequent Sundays at the same time.

New cast members in season four include Jeffrey Wright as Valentin Narcisse, a violent Harlem power broker who tries to muscle in on Chalky's action; Ron Livingston as Roy Phillips, a business and romantic prospect of Gillian's; Patricia Arquette as Sally Wheet, a Florida speakeasy owner; Brian Geraghty as Federal Agent Warren Knox; and Domenick Lombardozzi and Morgan Spector as Al Capone's brothers, Ralph and Frank.

Following his battle with Gyp Rosetti, Nucky makes a peace offering to Joe Masseria (Ivo Nandi) while working the odds with Arnold Rothstein. While Chalky is busy running the Onyx Club on the Boardwalk, the impulsive Dunn Purnsley (Erik LaRay Harvey) clashes with a booking agent. Fresh-faced Federal Agent Warren Knox arrives in Atlantic City to learn the ropes from Agent Sawicki (Joseph Aniska). Gillian seeks custody of her grandson, Tommy (Brady Noon), while trying to find a "good" man to keep the Artemis Club afloat. Eli's college-age son, Willie (Ben Rosenfield), turns to Nucky for career advice. Al Capone enlists his brothers, Frank and Ralph, to help him expand his business in the Chicago suburb of Cicero. Richard Harrow returns to his violent ways.

Now working as a "delivery man" for Dean O'Banion (Arron Shiver), Van Alden is ordered to keep tabs on Al Capone, joining the ascendant mobster to help keep Cicero voters "informed" at a political rally. Dr. Valentin Narcisse arrives in Atlantic City, clashing with Chalky and Nucky over the loss of an employee. In Washington, Agent Knox aligns himself with J. Edgar Hoover (Eric Ladin), acting director of the Bureau of Investigation. Harrow fails to finish a job in Milwaukee, while Eddie demands a promotion after 11 years of service. With a business opportunity on the horizon, Nucky departs for Florida.

Written by Dennis Lehane and Howard Korder; directed by Alik Sakharov.

Nucky has reservations about investing in a Tampa land deal engineered by transplanted bootlegger Bill McCoy (Pearce Bunting). While there, he meets speakeasy owner Sally Wheet. Valentin Narcisse books a sexy jazz singer, Daughter Maitland (Margot Bingham), to perform at the Onyx, and gauges Dunn Purnsley's allegiance to Chalky. Willie, Eli's son, turns to Mickey Doyle and his bootleg warehouse to elevate his social standing at college. Gillian agrees to pose as Roy Phillips' wife to impress a possible partner. Harrow tries to bury his past, though not before taking care of some unfinished business with Emma (Katherine Waterston).

Written by Terence Winter; directed by Allen Coulter.

Episode #40: "All In"

Debut: SUNDAY, SEPT. 29 (9:00-10:00 p.m.)

Other HBO playdate: Sept. 29 (11:00 p.m.)

HBO2 playdate: Sept. 30 (9:00 p.m.)

Nucky gets to know Arnold Rothstein over a card game, and sizes up an unexpected partner for his Tampa land deal. A newly promoted Eddie Kessler gets detoured after making a train-station delivery. When one of their collectors is incapacitated, Al and Frank Capone decide to finish his route, enlisting a reluctant Van Alden to tag along. Agent Knox fills Hoover in on the Thompson operation, vowing to exploit Nucky's weakest link. Chalky is intrigued by Daughter Maitland's presence. Dunn Purnsley goes to Harlem, and is courted by Valentin Narcisse. Willie and his college roommate, Clayton (Owen Campbell), carry a practical joke too far.

Written by David Matthews; directed by Ed Bianchi.

BOARDWALK EMPIRE recently received ten nominations for the upcoming 65th Primetime Emmy(R) Awards, including Outstanding Supporting Actor in a Drama Series (Bobby Cannavale) and Outstanding Directing for a Drama Series (Tim Van Patten).

In Sept. 2012, the show won four Emmys(R), including Outstanding Directing for a Drama Series (Tim Van Patten). In Sept. 2011, it received eight Emmys(R), the most of any program that year, including Outstanding Directing for a Drama Series (Martin Scorsese).

In Jan. 2011, BOARDWALK EMPIRE received two Golden Globe Awards, for Best Television Series - Drama and Best Performance by an Actor in a Television Series - Drama (Steve Buscemi).

Among the critical raves for the third season, which concluded in Dec. 2012, the Boston Globe hailed the show's "dazzling production" and "knockout performances," while New York's Daily News described it as "first-rate." Newsday termed the series "immensely entertaining," and Variety called it "as handsome, well cast and impeccably crafted as anything on TV."

For more on the series, visit Facebook.com/BoardwalkEmpire and Twitter @BoardwalkEmpire #BoardwalkEmpire.